The letters VS represent Vollnaben Schalenrahmen, which means full hub plate frame. This model, released onto the market in 1957 is also known as the VS 50 L (L representing Luxus). In 1959 the VS 50 De Luxe Sport model was released. A socalled "Belly Slider" model. In 1962 the Skyrider model came out and became one of the most well known models ever shipped. Most remarkable feature of this model was it's steering wheel with the small crossbar in it. Around and about 1965 the MS Skyway model was released. This was actually the old MS version with the heavier frame of the VS version.
Puch keeps on switching between the models and releases a Skyhunter model in 1969. This type was actually a VS model with a closed chain compartment and wider luggage rack.
Source: Berrie van Mier, Infonu.nl